1. Field of the Invention
The present invention concerns improvements to the hoisting assemblies including means for varying the relative angular position between the boom and the counterweight support.
2. Description of the Prior Art
U.S. Pat. No. 4,155,463 (the content of which is supposed incorporated here for reference) discloses a hoisting assembly designed in order to prevent a torque reaction on the assembly main support and comprising a boom and a counterweight support extending in an opposite direction with respect to the main support and interconnected by controllably adjustable connecting means adapted to selectively modify the relative angular position between the boom and the counterweight support, said boom and said counterweight support, together with the connecting means, forming a pendular assembly idly swinging around an horizontal swing axis on said main support so as to take a balanced position whatever the load carried by the boom is.